A colon imaging system, including an imaging capsule, having: a. a radiation source providing X-Ray and gamma radiation with energies sufficient to induce X-Ray fluorescence from nanoparticles that adhere to cancerous tissue, and which were administered to a patient in a solution prior to examining the colon with the imaging capsule; b. a detector for detecting particle energy of particles emitted responsive to the provided radiation and forming count information disclosing a number of particles detected for each energy level; c. a transceiver for transferring the count information to an external computer for analysis, and also having a computer for constructing images of an inside of the colon based on the count information; wherein the images provide an indication of locations in the colon of which the nanoparticles adhere to.